The development of a semiconductor gamma camera has been discussed for many years, because its improved energy resolution would result in improved scatter rejection, thereby improving spatial resolution. Further advantages for a semiconductor gamma camera would be increased ability to scan with multiple isotopes or isotopes with multiple photopeaks, and the possibility of a portable gamma camera. But limited progress has been made to date. The principle reason for the paucity of working devices has been the extreme demands put on semiconductor materials to be used for a gamma camera application. With recent availability of intrinsic or ultra pure germanium for use in gamma-ray detector applications at 77 k, new possibilities for gamma cameras have been made available. One promising approach has been suggested in theoretical studies by Hatch, made in this laboratory. These studies showed that a thin layer having a high sheet resistivity (10k/square), fabricated on the Ge surface, could be used with only 12 -18 peripheral contacts and associated amplifiers to achieve a resolution of 2-3mm over a 2" - 3" diameter field, albeit at a somewhat increased gamma ray exposure. Limited experiments support these results. It is proposed to construct and test an elementary position-sensitive detector after the proposed method of Hatch, using ion-implantation to produce the resistive layer on the intrinsic germanium. It is further proposed to study alternative ways of connecting these small position sensitive detectors into arrays capable of performing as a gamma camera. Finally, an evaluative study of the known parameters of newer radiation detector materials, such as HgI2 and polycrystalline CdTe sheets, as possible position sensitive detectors of the Hatch variety is proposed.